﻿
//Event, a simple class for implementing the Observer pattern
function Event(sender) {
    this._sender = sender;
    this._listeners = [];
}

Event.prototype = {
    attach : function (listener) {
        this._listeners.push(listener);
    },
    notify : function (args) {
        var index;

        for (index = 0; index < this._listeners.length; index += 1) {
            this._listeners[index](this._sender, args);
        }
    }
};

//This is the model - it stores items and notifies observers about change

//---------------MODEL----------------
function ListModel(items) {
    this._items = items;
    this._selectedIndex = -1;

    this.itemAdded = new Event(this);
    this.itemRemoved = new Event(this);
    this.selectedIndexChange = new Event(this);
}

ListModel.prototype = { 
    getItems : function() {
        return [].concat(this._items);
    },

    addItem : function(item) {
        this._items.push(item);
        this.itemAdded.notify({ item : item });
    },

    removeItemAt : function(index) { 
        var item;

        item = this._items[index];
        this._items.splice(index, 1);
        this.itemRemove.notify({ item : item });
        if(index == this._selectedIndex)
        {
            this.setSelectedIndex(-1);
        }
    },

    getSelectedIndex : function() {
        return this._selectedIndex;
    },

    setSelectedIndex : function(index) {
        var previousIndex;

        previousIndex = this._selectedIndex;
        this._selectedIndex = index;
        this.selectedIndexChanged.notify({previous : previousIndex};
    }
};


//---------------MODEL - END----------------


//---------------VIEW----------------

function.ListView(model, elements) {
    this._model = model;
    this._elements = elements;

    this.listModified = new Event(this);
    this.addButtonClicked = new Event(this);
    this.delButtonClicked = new Event(this);

    var _this = this;

    //Attach the model listeners
    //Attach rebuild
    this._model.itemAdded.attach(function() {
        _this.rebuildList();
    });
    //Remove rebuild
    this._model.itemRemoved.attach(function() {
        _this.rebuildList();
    });

    //Attach listeners to HTML controls
    this._elements.list.change(function(e) {
        _this.listModified.notify({ index : e.target.selectedIndex });
    });
    this._elements.addButton.click(function() {
        _this.addButtonClicked.notify();
    });
    this._elements.delButton.click(function() {
        _this.delButtonClicked.notify();
    });
}

ListView.prototype = {
    show : function () {
        this.rebuildList();
    },

    rebuildList : function () {
        var list, items, key;

        list = this._elements.list;
        list.html('');

        items = this._model.getItems();
        for (key in items) {
            if (items.hasOwnProperty(key)) {
                list.append($('<option>' + items[key] + '</option>'));
            }
        }
        this._model.setSelectedIndex(-1);
    }
};

//---------------VIEW - END----------------

//---------------CONTROLLER----------------

function ListController(model, view) {
    this._model = model;
    this._view = view;

    var _this = this;

    this._view.listModified.attach(function(sender,args) {
        _this.updateSelected(args.index);
    });

    this._view.addButtonClicked.attach(function() {
        _this.addItem();
    });

    this._view.delButtonClicked.attach(function() {
        _this.delItem();
    });

    ListController.prototype = {
        addItem : function() {
            var item = window.prompt('Add item:','');
            if(item)
            {
                this._model.addItem(item);
            }
    },

        delItem : function () {
            var index;
            index = this._model.getSelectedIndex();
            if (index !== -1) 
            {
                this._model.removeItemAt(this._model.getSelectedIndex());
            }
    },

    updateSelected : function (index) {
        this._model.setSelectedIndex(index);
    }


};

//---------------CONTROLLER - END----------------

//View and Controller instanciated:
             $(function () {
                var model = new ListModel(['PHP', 'JavaScript']),
                    view = new ListView(model, {
                        'list' : $('#list'), 
                        'addButton' : $('#plusBtn'), 
                        'delButton' : $('#minusBtn')
        }),
        controller = new ListController(model, view);
    
    view.show();
});​
